PROJECTSUMMARY/ABSTRACT The prevention of mother-to-child transmission of HIV (PMTCT) is the most successful HIV prevention intervention globally. In 2015, South Africa adopted the WHO?s ?Option B+? PMTCT strategy;? lifelong antiretroviral therapy (ART) for all HIV-positive pregnant and breastfeeding women, regardless of CD4 count.However,theearlyeffectivenessofPMTCT,especiallyinlowresourcesettingsislargelycentered on pregnant women and very early infant diagnosis with less emphasis on preventing transmission to infantsborntoHIV-positivewomeninfantsfurtheralongthePMTCTcascade.IntheCityofJohannesburg (CoJ), despite the recommendation in the South African National Department of Health (SANDoH) guidelinesforanintegratedapproachtomaternalandchildhealth,maternalHIVre-testingpostpartum, infanttestingbeyond10weeksandmaternalviralloadtestingarecurrentlynotwellintegratedintothe ExpandedProgrammeforImmunisation(EPI)eventhoughthepostpartumperiodisarecognisedhigh risk period for poor maternal adherence to ART and subsequent transmission of HIV to infants. The barriers to implementation of this integrated approach are largely unknown. Current programme indicators on infant HIV testing are difficult to interpret because of difficulties with data quality and accuratedenominators;?therearecurrentlynopostpartumprogrammeindicatorsonmaternalre-testing ormaternalviralloadmonitoring.PoorimplementationofpostpartumHIVtestingandmonitoringofHIV- infectedwomenand/orrecordingoftheseactivitieshasresultedinavoidofinformationonthematernal andinfantHIVincidenceinthepostpartumperiodinthishighmaternalHIVprevalencesetting.Finally, lowmalepartnerinvolvementinPMTCTprogrammesinSouthAfricaiswellrecognisedbuthasnotbeen effectivelyaddressedinoursetting.InordertoaddressthesegapstoPMTCTinthepostpartumperiod, the proposed study will apply the EPI-integrated approach recommended by the SANDoH to mother- infantpairs(MIP)withtheaimto:(1)estimatetheHIVincidenceandassociatedriskfactorsinwomen andinfants;?assessthedemand,practicalityandintegrationrequirementsforthisapproach,evaluatethe acceptability, accuracy and cost-effectiveness of an HIV rapid test in HIV-exposed infants;? (2) assess maternal viral load testing and adherence monitoring;? and (3) elucidate female perspectives on male partnerinvolvementinPMTCTandHIVtesting.Thisstudywillbeconductedoveraperiodof24months insub-districtFoftheCoJ,ahighHIVburdenHIVPEPFARprioritydistrict.Thedataobtainedfromthis study will be used to develop an EPI-integrated HIV testing and management algorithm, aimed at increasing the implementation, uptake and understanding of postpartum aspects of mother-infant HIV careandprevention.